Here is my thought, write a new script for the audiozone, the timer length being the length of the audio clip. At the end, have it activate the door, and script the door so when activated, it is possible for the player to open it
My thoughts:
:state=0:hudreset,hudx=50,hudy=90,hudimagefine=gamecore\text\pressentertouse.tga,hudname=keydoorprompt,hudhide=1,hudmake=display,state=20
:state=20,activated=1:state=10
:state=10,plrdistwithin=60:hudshow=keydoorprompt,hudfadeout=keydoorprompt
:state=10,plrdistwithin=60,plrusingaction=1:state=1,setframe=0,sound=$0
:state=1:incframe=0
:state=1,frameatend=0:state=2,coloff
:state=2,plrdistfurther=60:state=3,sound=$1,colon
:state=3:decframe=0
:state=3,frameatstart=0:state=10,setframe=0
^for the door main, is modified locked door script^
:state=0,plrwithinzone=1:sound=$0,timerstart,state=1
:state=1,timergreater=(time here):activateifused=1
^audio zone - set door name as ifused property^
Generally I dont give out scripts but I need practice. I haven't tested, but it should work.